1. Agreed they accomplish the same goal, less equipment, reducing the complexity, provides a minimal amount of extra surface area for gas exchange in regards to your manifold ( if this is making a difference your system is likely inadequate to being with), provides more even distribution of nutrients from the epi (possible help for larger plants and systems only smaller systems are not likely to see much of a benefit in that regard)I think you're missing my point. Waterfalls don't increase oxygenation- full saturation is actually easy to achieve.
The advantages I found with waterfalls were many;
1. Less equipment to accomplish the same goal, thereby reducing complexity, cost and points of potential failure. RDWC requires a circulation pump anyway, so I just use that same unit attached to a manifold to evenly distribute water to all tubs- advantage being that whatever I add to the control bucket is immediately and evenly mixed- and that manifold also oxygenates because it feeds a waterfall in every tubsite.
2. I've found this approach makes the plants much less sensitive to changes in the water level, again improving robustness in the system.
3. I had root rot problems when I used airstones, and like everyone else I employed water chilling to prevent it. With waterfalls, no such problems and water chilling was no longer necessary, again leading to much lower costs, more robust operation and lower parts count.
Whether this makes sense to you or not, it works, at scale, reliably and repeatably. No magic. When empirical results differ from theory, one must reexamine the assumptions one is operating under. Waterfalls work; Mother Nature has been using them for a long time.
Disagreed that it reduces cost, if you are going to run 1 pump maybe but again i don't feel its a good idea to have all your eggs in one basket. You will also require a bigger pump due to the increased head pressure further increasing the cost because you change from pulling water through the system to pushing it through this compounds as the system gets bigger if you want to keep the same flow.
Disagreed on points of failure, you are putting all of your eggs in one basket with one pump unless you run 2 pumps increasing the cost. If an air pump fails it still has the circulation of the water and while O2 exchange will be drastically reduced it will not be almost completely eliminated like if you are running one water pump. With an air stone if your water pump fails the water stays oxygenated and not stagnant, the only concern would be it depleted the nutrients which would allow for a lot of time before serious problems occur in comparison to without an air stone.
2. I can't see any logical reason for this, other than splashing the roots. Both provide this effect in different ways but i guess i could possibly the effect increasing as water level drop on a waterfall system.
3. There could be many reasons why you had problems when you used air stones. Likely an inadequate system by some means (which i can't say, maybe volume, maybe air stone placement (doubtful you seem to know your stuff), maybe the size of your containers, maybe plugged up air stones, maybe multiple of these issues) If you are generating a root mass that takes up almost the whole container I can see most definitely a waterfall being more effective but that's not an air stone issue.
Water temp is directly related to the amount of DO water holds. All we are doing is replenishing it so the more o2 you start out with the bigger buffer you have and the further you drift from equilibrium the faster this occurs provided you have adequate gas exchange this is fact. If you think you are adding o2 in excess of what it holds at equilibrium you have been misinformed on the subject somewhere along the way. o2 is very had to raise above equilibrium without increased pressure or temp change. (Not deleting this portion for information purposes but i just reviewed you post and this was not something you were claiming)
If i had to guess why you see such a difference (i believe you have seen a big difference and believe most of what you claim to have seen a difference in but not for the reason you are claiming that is my issue because people take them as fact after and that how all this misinformation gets spread) is because your previous equipment or air system was not adequate that could be for many different reason (some i have listed).
I want to apologize for my reaction and some uncalled for remarks. I would much rather debate like this. I got triggered and that's on me. We don't have to agree on everything and a healthy debate helps the community as a whole. So i take full responsibility for turning what should have been a healthy debate into a shit show
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